1. Field of the Invention
This invention generally relates to information compressing apparatus and method. This invention particularly relates to a method and an apparatus for compressively encoding an information signal including at least a video signal. Also, this invention relates to a method and an apparatus for processing a video signal.
2. Description of the Related Art
A prior-art information compressing apparatus in an MPEG (Moving Picture Experts Group) system compressively encodes a stream of original pictures each assigned to one of first, second, and third types. The first type corresponds to I-pictures (intra-coded pictures). The second type corresponds to P-pictures (predictive-coded pictures). The third type corresponds to B-pictures (bidirectionally predictive-coded pictures). The prior-art information compressing apparatus implements a compressing process GOP by GOP, where GOP means a group of pictures. Every GOP is composed of one I-picture and at least one P-picture or one B-picture. For every GOP, an I-picture is encoded first even in the case where the I-picture occupies a second or later picture place within the GOP.
As the numbers of original pictures in GOP""s increase, the qualities of encoding-resultant pictures rise. As the numbers of original pictures in GOP""s increase, units of the compressing process increase so that units of editing picture information also increase. The increased units make fine editing difficult. On the other hand, as the numbers of original pictures in GOP""s decrease, the qualities of encoding-resultant pictures drop.
It is assumed that editing causes encoding to pause at a P-picture in a GOP which follows an I-picture therein in the order of encoding. When encoding is restarted, it is necessary to commence encoding from the I-picture in that GOP again. Accordingly, in this case, the encoding of the I-picture is executed twice, and hence the efficiency of editing-related encoding work tends to be low.
It is an object of this invention to provide an improved information compressing apparatus.
It is another object of this invention to provide an improved method of compressing information.
A first aspect of this invention provides an information processing apparatus comprising an address generation circuit for generating an address signal; a memory for storing an information signal containing a video signal in response to the address signal generated by the address generation circuit; first means for periodically updating the address signal generated by the address generation circuit; a compression processing circuit for reading out the information signal from the memory, and subjecting the read-out information signal to a compressively encoding process; second means for detecting a head of every frame represented by the information signal; third means for storing a state of the address signal generated by the address generation circuit which corresponds to the frame head detected by the second means; fourth means for detecting whether or not the information signal becomes discontinuous; fifth means for suspending operation of the first means and also operation of the compression processing circuit when the fourth means detects that the information signal becomes discontinuous; sixth means for detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous; and seventh means for starting the updating of the address signal by the first means from the state stored by the third means when the sixth means detects that the information signal returns to its normally continuous state after the information signal becomes discontinuous.
A second aspect of this invention is based on the first aspect thereof, and provides an information processing apparatus wherein the fourth means comprises a sync separator for separating a first sync signal from the information signal; a PLL circuit for generating a second sync signal in response to the first sync signal; and a comparator for comparing the first sync signal and the second sync signal to detect whether or not the information signal becomes discontinuous.
A third aspect of this invention is based on the first aspect thereof, and provides an information processing apparatus wherein the fourth means comprises an encoding pause button; and means for detecting whether or not the information signal becomes discontinuous in response to a position of the encoding pause button.
A fourth aspect of this invention is based on the first aspect thereof, and provides an information processing apparatus wherein the sixth means comprises an encoding pause button; and means for detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous in response to a position of the encoding pause button.
A fifth aspect of this invention provides an information processing apparatus comprising a first address generation circuit for generating a first address signal corresponding to a pixel; a second address generation circuit for generating a second address signal corresponding to a frame; a memory for storing an information signal containing a video signal in response to the first address signal and the second address signal generated by the first address generation circuit and the second address generation circuit; first means for periodically updating the first address signal generated by the first address generation circuit; second means for updating the second address signal generated by the second address generation circuit in response to the first address signal generated by the first address generation circuit; a compression processing circuit for reading out the information signal from the memory, and subjecting the read-out information signal to a compressively encoding process; third means for detecting a head of every frame represented by the information signal; fourth means for detecting whether or not the information signal becomes discontinuous; fifth means for suspending operation of the first means and also operation of the compression processing circuit when the fourth means detects that the information signal becomes discontinuous; sixth means for returning the first address signal to a predetermined initial state when the fourth means detects that the information signal becomes discontinuous; seventh means for detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous; and eighth means for, in cases where the seventh means detects that the information signal returns to its normally continuous state after the information signal becomes discontinuous, starting the updating of the first address signal by the first means from the predetermined initial state when the third means detects a frame head.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides an information processing apparatus wherein the fourth means comprises a sync separator for separating a first sync signal from the information signal; a PLL circuit for generating a second sync signal in response to the first sync signal; and a comparator for comparing the first sync signal and the second sync signal to detect whether or not the information signal becomes discontinuous.
A seventh aspect of this invention is based on the fifth aspect thereof, and provides an information processing apparatus wherein the fourth means comprises an encoding pause button; and means for detecting whether or not the information signal becomes discontinuous in response to a position of the encoding pause button.
An eighth aspect of this invention is based on the fifth aspect thereof, and provides an information processing apparatus wherein the seventh means comprises an encoding pause button; and means for detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous in response to a position of the encoding pause button.
A ninth aspect of this invention provides an apparatus comprising first means for detecting whether or not a first video signal becomes discontinuous and hence a defective frame picture occurs in a stream of frame pictures represented by the first video signal; and second means for removing the defective frame picture from the stream of frame pictures to change the first video signal into a second video signal representing the stream of frame pictures except the defective frame picture.
A tenth aspect of this invention provides a method comprising the steps of generating an address signal; storing an information signal into a memory in response to the address signal, the information signal containing a video signal; periodically updating the address signal; reading out the information signal from the memory, and subjecting the read-out information signal to a compressively encoding process; detecting a head of every frame represented by the information signal; storing a state of the address signal which corresponds to the detected frame head; detecting whether or not the information signal becomes discontinuous; suspending the updating of the address signal, and also the reading-out of the information signal from the memory and the subjecting of the read-out information signal to the compressively encoding process when it is detected that the information signal becomes discontinuous; detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous; and starting the updating of the address signal when it is detected that the information signal returns to its normally continuous state after the information signal becomes discontinuous.
An eleventh aspect of this invention provides a method comprising the steps of generating a first address signal corresponding to a pixel; generating a second address signal corresponding to a frame; storing an information signal into a memory in response to the first address signal and the second address signal, the information signal containing a video signal; periodically updating the first address signal; updating the second address signal in response to the first address signal; reading out the information signal from the memory, and subjecting the readout information signal to a compressively encoding process; detecting a head of every frame represented by the information signal; detecting whether or not the information signal becomes discontinuous; suspending the updating of the first address signal, and also the reading-out of the information signal from the memory and the subjecting of the read-out information signal to the compressively encoding process when it is detected that the information signal becomes discontinuous; returning the first address signal to a predetermined initial state when it is detected that the information signal becomes discontinuous; detecting whether or not the information signal returns to a normally continuous state after the information signal becomes discontinuous; and in cases where it is detected that the information signal returns to its normally continuous state after the information signal becomes discontinuous, starting the updating of the first address signal from the predetermined initial state when a frame head is detected.
A twelfth aspect of this invention provides a method comprising the steps of detecting whether or not a first video signal becomes discontinuous and hence a defective frame picture occurs in a stream of frame pictures represented by the first video signal; and removing the defective frame picture from the stream of frame pictures to change the first video signal into a second video signal representing the stream of frame pictures except the defective frame picture.